The present invention relates to an apparatus which can be used for local electrolytic polishing and which can be moved manually or connected to a moving mechanism. The apparatus is equipped with an electrically insulated handle, and it is intended substantially for the electrolytic polishing of areas of surface damage possibly produced during the transport and/or handling of large polished pieces and/or unpolished surfaces produced during the joining of large polished pieces. The apparatus can be used for polishing large continuous surfaces when it is connected to a moving mechanism.
U.S. Pat. No. 4,176,036 discloses an electrode for local electrolytic coating. This coating apparatus is intended for electrolytic coating by a relatively soft metal. The said soft metal serves as an anode in the circuit. The coating apparatus has an electrolytically insulated handle and a beam member of a substantially harder metal, attached to the handle. The beam member, furthermore, has a number of conical openings. The anode of the circuit is in close contact with one side of the beam member, and the anode has protrusions which completely fill the openings in the beam part. The protrusions have flat terminal areas, and on the center line of the terminal areas they extend, at the level of the other side of the beam, towards the conical openings and keep the anode of soft metal in close contact with the beam part.
It is known that large pieces can be surface treated, e.g. polished, in stages as follows:
1. By dividing the piece into as small parts as possible and by polishing each part separately and not attaching the parts to each other until they are at their place of use,
2. by dividing the piece into a few smaller partial entities and by carrying out the further treatment as in point 1,
3. by polishing the piece when the piece is whole.
The polishing of a large, massive piece as a whole in accordance with point 3 is difficult, since the size of the polishing tanks sets its limitations. In addition, the costs incurred from the polishing of a large piece are high, since large amounts of polishing electrolyte are necessary. Furthermore, the transportation of a large piece from the polishing place to the place of use is difficult.
After the polishing of the parts and/or partial entities of a large piece in accordance with points 1 and 2, the parts and/or partial entities are advantageously not attached to each other by mechanical attachment members and/or, for example, by welding until they are at their place of use. Owing to the handling and/or transportation, unpolished surfaces are produced in the piece, and the polishing of these surfaces is no longer possible or profitable in a normal electrolytic tank, since the surfaces are small compared with the surface area of the entire large piece. Also, a surface fulfilling special requirements is usually not obtained by mere mechanical polishing of the surfaces.
The object of the present invention is to provide an apparatus for electrolytic polishing, the apparatus being easy to move as compared with the state of the art described above. Electrolytic polishing requires a continuous supply of a liquid electrolyte, which must remain continuously between the electrodes, i.e. the cathode and the anode. Binding of the electrolyte is not required in polishing according to the state of the art described above, since the pieces to be polished are immersed in the electrolytic tank. Keeping the liquid electrolyte between the electrodes in tanks intended for polishing causes no difficulty, but when a movable electrode is used, the problem is how to polish continuously without stoppages due to the addition of electrolyte.